Dataguard

Enables ‘non-stop’ and ‘known state’ computing—This process periodically pauses activity to enable markers to be set which record the fact that the database is at a known point at that specific time. The recovery modules can refer to these checkpoints to keep the system in a robust state.

Allows backups to take place without the need to close down the system—Online backup negates the need for users to be taken offline by backing up the database content while system usage continues. Backup and restore can be performed without the need to shutdown activity on the database server. The backup will be a complete copy of the database at the point in time when the backup process finished. This backup is guaranteed to be in a consistent state because of the Checkpointing feature. The Restore command can also be used on a live system.

Resilient and automatically resizable file system—In badly sized hash files data is frequently split across a number of different frames and all must be read from and written to disk when the data changes. If something goes wrong there is a significant chance that an update will be interrupted and the structure of the file corrupted. In jBASE Release 5, a new resilient file type has been introduced to eliminate this possibility. In a resilient file, where data spans across disk frames, it is built up in a separate area of the file and flushed to disk. Only once it is on disk is a pointer updated to the new data structure rather than the old structure.

As well as being resilient, jR files also resize automatically. This is achieved by separating the location of the data from the record key of the file. This means that the structure of the underlying data can expand without having to redistribute all the data as was the case with previous hash files.

The ability to bring a failed system back into play automatically—This feature enables a failed system to be automatically recovered to a known state in the shortest possible time, thereby reducing the length of down-time and the knock on effect on the business. A jBASE 4 database can be recovered by restoring the last backup and replaying the transaction journal but requires manual intervention. Warmstart enables jBASE 5 to automatically recover from events such as power failures in a similar way to mainstream RDBMS products.